U.S. patent application number 14/591435 was filed with the patent office on 2015-07-09 for gate-boosting rectifier and method of permitting current to flow in favor of one direction when driven by ac input voltage.
The applicant listed for this patent is NATIONAL CHIAO TUNG UNIVERSITY. Invention is credited to I-No Liao, Chatrpol Pakasiri, Chao-Han Tsai, Yu-Jiu Wang.
Application Number | 20150194907 14/591435 |
Document ID | / |
Family ID | 53495954 |
Filed Date | 2015-07-09 |
United States Patent
Application |
20150194907 |
Kind Code |
A1 |
Wang; Yu-Jiu ; et
al. |
July 9, 2015 |
GATE-BOOSTING RECTIFIER AND METHOD OF PERMITTING CURRENT TO FLOW IN
FAVOR OF ONE DIRECTION WHEN DRIVEN BY AC INPUT VOLTAGE
Abstract
A current-rectifying device includes a switching component and
an impedance transformer. A conductance between first and second
nodes of the switching component is controlled based on a voltage
between high-impedance control and control-reference nodes of the
switching component to determine an amount of current that is
permitted to flow between the first and second nodes. The impedance
transformer includes a positive input node electrically connected
to one of the first and second nodes based on AC voltage swings, a
negative input node, a positive output node electrically connected
to the high-impedance control node, and a negative output node, and
which senses an AC voltage swing derived from the AC input voltage
with the positive input node and the negative input node, and
provides an AC voltage swing between the high-impedance control and
control-reference nodes that is greater than the AC voltage swing
derived from the AC input voltage.
Inventors: |
Wang; Yu-Jiu; (Hsinchu,
TW) ; Liao; I-No; (Hsinchu, TW) ; Tsai;
Chao-Han; (Hsinchu, TW) ; Pakasiri; Chatrpol;
(Hsinchu, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NATIONAL CHIAO TUNG UNIVERSITY |
Hsinchu |
|
TW |
|
|
Family ID: |
53495954 |
Appl. No.: |
14/591435 |
Filed: |
January 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61924324 |
Jan 7, 2014 |
|
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|
Current U.S.
Class: |
363/127 |
Current CPC
Class: |
H02M 7/25 20130101; H02M
7/19 20130101 |
International
Class: |
H02M 7/217 20060101
H02M007/217 |
Claims
1. A current-rectifying device which permits a current to flow in
favor of one direction when driven by an AC input voltage,
comprising: a switching component including a first node, a second
node, a control-reference node and a high-impedance control node,
wherein a conductance between the first node and the second node is
controlled based on a voltage between the high-impedance control
node and the control-reference node, and an amount of a current
that is permitted between the first node and the second node is
thus determined; and an impedance transformer including a positive
input node, a negative input node, a positive output node and a
negative output node, wherein the positive input node is
electrically connected to one of the first node and the second node
based on AC voltage swings thereof, and the positive output node is
electrically connected to the high-impedance control node, such
that the impedance transformer senses an AC voltage swing derived
from the AC input voltage with the positive input node and the
negative input node, and provides an AC voltage swing between the
high-impedance control node and the control-reference node that is
greater than the AC voltage swing derived from the AC input
voltage, and an AC voltage swing between the first node and the
second node is substantially in phase with the conductance
therebetween to permit the current driven by the AC input voltage
to flow in favor of a direction from the first node to the second
node.
2. The current-rectifying device of claim 1, wherein the switching
component is a field-effect transistor (FET), a bulk node of the
FET serves as the control-reference node, and a gate node of the
FET serves as the control node.
3. The current-rectifying device of claim 2, further comprising a
biasing circuit electrically connected to the high-impedance
control node for reducing an effective threshold voltage of the
FET, wherein the high-impedance control node and the positive
output node are electrically connected through a capacitor.
4. The current-rectifying device of claim 3, wherein the biasing
circuit comprises: a diode-electrically connected transistor; a
first resistor electrically connected to the diode-electrically
connected transistor to provide a bias voltage when a current
generated by the diode-electrically connected transistor flows
through the first resistor; and a second resistor electrically
connected to a node between the diode-electrically connected
transistor and the first resistor.
5. The current-rectifying device of claim 1, wherein the switching
component is a bipolar-junction transistor (BJT), and a base node
of the BJT serves as the high impedance control node.
6. The current-rectifying device of claim 1, wherein the first node
is an anode, and the second node is a cathode.
7. The current-rectifying device of claim 1, wherein the
control-reference node is electrically connected to one of the
first node and the second node based on a conducting type of the
switching component.
8. The current-rectifying device of claim 1, wherein the switching
component further comprises a bias node for adjusting the
conductance between the first node and the second node.
9. The current-rectifying device of claim 1, wherein the AC voltage
swing between the positive input node and the negative input node
is amplified through the impedance transformer to become a greater
AC voltage swing between the positive output node and the negative
output node when a parasitic impedance from the high-impedance
control node is loaded.
10. The current-rectifying device of claim 9, wherein the impedance
transformer presents a substantially 0.degree. or 180.degree. phase
shift based on a phase of the AC voltage swing between the positive
input node and the negative input node.
11. The current-rectifying device of claim 9, wherein the impedance
transformer comprises: a transformer unit having a first coil and a
second coil, wherein a turn ratio of the first coil to the second
coil is 1 to a positive number N; a first input capacitor
electrically and serially connected between the positive input node
and the first coil; and a shunt capacitor electrically connected
between the positive output node and the negative output node and
parallel to the second coil.
12. The current-rectifying device of claim 11, wherein the shunt
capacitor is a parasitic capacitor contributed from an output load
thereof.
13. The current-rectifying device of claim 11, further comprising a
second input capacitor electrically and serially connected between
the negative input node and the first coil.
14. The current-rectifying device of claim 11, wherein the negative
output node is electrically connected to the negative input
node.
15. The current-rectifying device of claim 9, wherein the negative
output node is electrically connected to the negative input
node.
16. The current-rectifying device of claim 15, wherein the
impedance transformer comprises: a first inductor electrically
connected to the positive input node; a second inductor
electrically and serially connected between the first inductor and
the positive output node; a first shunt capacitor electrically
connected across an internal node, electrically and serially
connected between the first inductor and the second inductor, and
the negative input node; and a second shunt capacitor electrically
connected between the positive output node and the negative output
node.
17. A rectifier, which converts AC signals to an output DC current,
the rectifier comprising: an AC input node; a first capacitor with
one end electrically connected to the AC input node; a DC input
node; a first current-rectifying device according to claim 1,
wherein the first node of the first current-rectifying device is
electrically connected to the DC input node, and the second node of
the first current-rectifying device is electrically connected to
the other end of the first capacitor; a DC output node; a second
current-rectifying device according to claim 1, wherein the first
node of the second current-rectifying device is electrically
connected to the other end of the first capacitor, and the second
node of the second current-rectifying device is electrically
connected to the DC output node; a ground node; and a second
capacitor electrically connected across the DC output node and the
ground node.
18. The current-rectifying device of claim 17, wherein at least one
of the switching components of the first and second
current-rectifying devices further comprises a bias node for
adjusting the conductance between the first node and the second
node.
19. The current-rectifying device of claim 17, wherein the
impedance transformer of the first current-rectifying device and
the impedance transformer of the second current-rectifying device
are merged into one equivalent impedance transformer, such that an
AC output voltage swing of the equivalent impedance transformer is
shared by using AC coupling capacitors electrically connected
between equivalent output nodes of the equivalent impedance
transformer and the high impedance control nodes of the switching
components in the first and second current-rectifying devices.
20. The current-rectifying device of claim 17, further comprising:
an RF input node for electrically connected to an external RF
source; and a matching network electrically connected to the RF
input node for matching the external RF source from the RF input
node to the AC input node, to reduce a power reflection from the AC
input node.
21. A multi-stage rectifier, which converts AC signals to an output
DC current, each rectifier being constructed according to the
rectifier of claim 17, the multi-stage rectifier comprising: a
multi-stage AC input node; a multi-stage DC positive output node; a
multi-stage DC negative output node; a first rectifier, wherein the
DC input node of the first rectifier is electrically connected to
the multi-stage DC negative output node; and a second rectifier,
wherein the DC output node of the first rectifier is electrically
connected to the DC input node of the second rectifier, and the DC
output node of the second rectifier is electrically connected to
the multi-stage DC positive output node, and wherein the AC input
nodes of the first and second rectifiers are electrically connected
to the multi-stage AC input node.
22. The multi-stage rectifier of claim 21, further comprising a
third rectifier electrically connected between the first rectifier
and the second rectifier, wherein the output DC node of the first
rectifier is electrically connected to the DC input node of the
third rectifier, and the output DC node of the third rectifier is
electrically connected to the DC input node of the second
rectifier.
23. The multi-stage rectifier of claim 22, wherein at least one of
the switching components further comprises a bias node for
adjusting the conductance between the first node and the second
node thereof.
24. The multi-stage rectifier of claim 23, wherein at least one of
the bias node of the switching component is biased by a node which
is not one of the multi-stage DC positive output node, and the
multi-stage DC negative output node according to a conducting type
of the switching component.
25. The multi-stage rectifier of claim 21, wherein the impedance
transformers of the current-rectifying devices are merged into one
equivalent impedance transformer, such that AC output voltage
swings of the impedance transformers are shared by using AC
coupling capacitors electrically connected between equivalent
output nodes of the equivalent impedance transformer and the high
impedance control nodes of the switching components in the
current-rectifying devices.
26. The multi-stage rectifier of claim 21, further comprising: an
RF input node; and means for electrically connecting an external RF
source to the RF input node, and matching the external RF source
from the RF input node to the multi-stage AC input node to reduce a
power reflection from the multi-stage AC input node.
27. A method for permitting a current to flow in favor of one
direction when driven by an AC input voltage, comprising: providing
a switching component, which has a first node, a second node and a
control node; electrically connecting the first node to the AC
input voltage; electrically connecting an impedance transformer to
one of the first node and the second node based on AC voltage
swings thereof; and outputting an AC voltage swing substantially in
phase with a conductance of the switching component from the
impedance transformer to the control node of the switching
component.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims under 35 U.S.C. .sctn.119(a) the
benefit of U.S. Provisional Application No. 61/924,324, filed Jan.
7, 2014, the entire contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to rectifying devices, and, more
particularly, to a rectifying device which permits a current to
flow in favor of one direction when driven by an AC input voltage
and to an in-phase gate-boosting rectifier (IGR) which converts an
AC input voltage to an output DC current based on the rectifying
device.
[0004] 2. Description of Related Art
[0005] In the application of RF-to-DC rectifiers, the dimensions of
antenna can be reduced by increasing operating frequency. However,
as the frequency increases, the sensitivity of the rectifiers drops
quickly because the parasitic capacitance from the passive and the
active devices starts to dominate.
[0006] In order to improve the high-frequency performance of the
rectifiers, a diode with reduced forward voltage drop and reverse
leakage current is desired to improve sensitivity. In some
approaches, a two-terminal diode can be implemented using a
diode-connected MOSFET, and the forward voltage drops can be
reduced by reducing the rectifying a threshold voltage of a
transistor. However, due to the threshold voltage issue, the output
current of the transistor diode will be generated only when an
instantaneous V.sub.in is greater than the MOSFET threshold voltage
V.sub.th, which greatly influences the sensitivity.
[0007] Although the threshold voltage V.sub.th can be reduced by
providing a gate bias voltage, a large bias voltage not only
reduces effective threshold voltage, but also increases reverse
leakage current. Moreover, since all internal voltages are
initially zero, the input voltage swing still needs to be higher
than the threshold voltage V.sub.th for starting up.
[0008] In order to generate a larger MOSFET gate voltage swing from
the input voltage swing, an inductive peaking method has been
proposed. The inductive peaking method approach utilizes an
inductor to generate a larger gate voltage swing, so as to address
to the starting up issue. However, in this method the gate-source
voltage V.sub.GS and drain-source voltage V.sub.DS are not in
phase, such that excessive reverse leakage current will be
generated. Also, the input impedance of the rectifier is low due to
a series gate inductor and gate capacitor resonant circuit, and
such low resonant impedance will shunt between drain and source and
reduce the voltage swing of V.sub.DS.
[0009] From the foregoing, how to find a way to provide a diode
with reduced forward voltage drop and reverse leakage current
becomes the objective being pursued by persons skilled in the
art.
SUMMARY OF THE INVENTION
[0010] Given abovementioned defects of the prior art, the present
invention provides an in-phase gate-boosting rectifier based on the
proposed rectifying device which use a impedance transformer to
permit current in favor of one direction when driven by an AC input
voltage, and as a consequence to improve the performance of a
rectifier.
[0011] In order to achieve abovementioned and other objectives, the
present invention provides a current-rectifying device which
permits a current to flow in favor of one direction when driven by
an AC input voltage. The current-rectifying device comprises a
switching component and an impedance transformer. The switching
component includes a first node, a second node, a control-reference
node and a high-impedance control node. A conductance between the
first node and the second node is controlled based on a voltage
between the high-impedance control node and the control-reference
node, and an amount of a current that is permitted between the
first node and the second node is thus determined. The impedance
transformer comprises a positive input node, a negative input node,
a positive output node and a negative output node. The positive
input node is electrically connected to one of the first node and
the second node based on AC voltage swings thereof, and the
positive output node is electrically connected to the
high-impedance control node. The impedance transformer senses an AC
voltage swing derived from the AC input voltage with the positive
input node and the negative input node, and provides an AC voltage
swing between the high-impedance control node and the
control-reference node that is greater than the AC voltage swing
derived from the AC input voltage. An AC voltage swing between the
first node and the second node is substantially in phase with the
conductance therebetween to permit the current driven by an AC
input voltage to flow in favor of the direction from the first node
to the second node.
[0012] In an embodiment, the switching component is a field-effect
transistor (FET), a bulk node of the FET serves as the
control-reference node, and a gate node of the FET serves as the
control node.
[0013] The present invention also provides a rectifier which
converts AC signals to an output DC current, the rectifier
comprising an AC input node, a first capacitor with one end
electrically connected to the AC input node, a DC input node, a
first current-rectifying device aforementioned, a DC output node, a
second current-rectifying device aforementioned, a ground node, and
a second capacitor electrically connected across the DC output node
and the ground node. The first node of the first current-rectifying
device is electrically connected to the DC input node, and the
second node of the first current-rectifying device is electrically
connected to the other end of the first capacitor. Also, the first
node of the second current-rectifying device is electrically
connected to the other end of the first capacitor, and the second
node of the second current-rectifying device is electrically
connected to the DC output node.
[0014] Moreover, the present invention provides a multi-stage
rectifier, which converts AC signals to an output DC current, the
multi-stage rectifier comprising a multi-stage AC input node, a
multi-stage DC positive output node, a multi-stage DC negative
output node, a first rectifier aforementioned, and a second
rectifier aforementioned. The input DC node of the first rectifier
is electrically connected to the multi-stage DC negative output
node. The output DC node of the first rectifier is electrically
connected to the DC input node of the second rectifier, and the DC
output node of the second rectifier is electrically connected to
the multi-stage DC positive output node, and wherein the AC input
nodes of the first and second rectifiers are electrically connected
to the multi-stage AC input node.
[0015] The present invention further provides a method of
permitting a current to flow in favor of one direction when driven
by an AC input voltage, comprising: providing a switching component
that has a first node, a second node and a control node;
electrically connecting the first node to the AC input;
electrically connecting an impedance transformer to one of the
first node and the second node based on AC voltage swings thereof;
and outputting an AC voltage swing substantially in phase with a
conductance of the switching component from the impedance
transformer to the control node of the switching component.
BRIEF DESCRIPTION OF DRAWINGS
[0016] The present invention can be more fully understood by
reading the following detailed description of the preferred
embodiments, with reference made to the accompanying drawings,
wherein:
[0017] FIG. 1 is a system structure view of a current-rectifying
device according to the present invention;
[0018] FIG. 2 is a schematic circuit of the current-rectifying
device according to an embodiment of the present invention;
[0019] FIG. 3 is a schematic circuit of the current-rectifying
device according to an embodiment of the present invention;
[0020] FIG. 4 is a schematic circuit of the current-rectifying
device having a biasing circuit according to an embodiment of the
present invention;
[0021] FIG. 5 is a schematic circuit of the biasing circuit of FIG.
4;
[0022] FIG. 6 is a schematic circuit of an impedance transformer
according to an embodiment of the present invention;
[0023] FIG. 7 is a schematic circuit of the impedance transformer
according to an embodiment of the present invention;
[0024] FIG. 8 is a schematic circuit of a rectifier according to
the present invention;
[0025] FIG. 9 is a schematic circuit of the rectifier according to
an embodiment of the present invention;
[0026] FIG. 10 is a schematic circuit of the rectifier according to
an embodiment of the present invention;
[0027] FIG. 11 is a schematic circuit of a multi-stage rectifier
according to the present invention;
[0028] FIG. 12 is a schematic circuit of a multi-stage rectifier
according to an embodiment of the present invention;
[0029] FIG. 13 is a scheme view of an equivalent impedance
transformer according to an embodiment of the present invention;
and
[0030] FIG. 14 is a schematic circuit of the multi-stage rectifier
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] In the following, specific embodiments are provided to
illustrate the detailed description of the present invention. Those
skilled in the art can easily conceive the other advantages and
effects of the present invention, based on the disclosure of the
specification. The present invention can also be carried out or
applied by other different embodiments.
[0032] As shown in FIG. 1, a system structure view of a
current-rectifying device 100 according to the present invention is
illustrated. The current-rectifying device 100 includes a switching
component 110 and an impedance transformer 120 which serves as a
passive in-phase voltage multiplier network. The switching
component 110 includes a first node 111, a second node 112, a
high-impedance control node 113 and a control-reference node 114,
for controlling an amount of a current I.sub.DC that flows through
the first node 111 and the second node 112. For example, the
conductance between the first node 111 and the second node 112 can
be controlled based on a voltage between the high-impedance control
node 113 and the control-reference node 114, such that an amount of
the current I.sub.DC permitted to flow between the first node 111
and the second node 112 can be determined.
[0033] When an AC input voltage V.sub.AC is applied to the first
node 111 and ac-coupled to the high-impedance control node 113, a
voltage swing at the high-impedance control node 113 needs to be
sufficiently large to permit the current I.sub.DC to flow from the
first node 111 to the second node 112 due to a starting up problem
caused by the threshold voltage of the switching component 100.
Accordingly, the impedance transformer 120 having a positive input
node 121, a negative input node 122, a positive output node 123 and
a negative output node 124 is provided to amplify the AC input
voltage V.sub.AC with a gain A.sub.v when a parasitic impedance
from the high-impedance control node 103 is loaded, so as to
increase the voltage swing between the high-impedance control node
113 and the control-reference node 114.
[0034] For example, the positive input node 121 is electrically
connected to the first node 111, and the positive output node 123
is electrically connected to the high-impedance control node 113.
It should be appreciated that the positive input node 121 is not
limited to be electrically connected to the first node 111. For
instance, if the voltage swing at the second node 112 is greater
than the voltage swing at the first node 111, the positive input
node 121 can be electrically connected to the second node 112 to
better increase the voltage swing between the high-impedance
control node 113 and the control reference node 114.
[0035] Given the above configuration, the impedance transformer 120
can sense an AC voltage swing derived from the AC input voltage
V.sub.AC through the positive input node 121 and the negative input
node 122, and provide a greater AC voltage swing between the
high-impedance control node 113 and the control-reference node 114.
As such, the conductance between the first node 111 and the second
node 112 is substantially in phase with the voltage swing
therebetween, so as to obtain a greater magnitude of the AC voltage
swing between the control node 113 and the control-reference node
114.
[0036] In such way, an instantaneous current flowing from the first
node 111 to the second node 112 is increased, and an instantaneous
current flowing from the second node 112 to the first node 111 will
be suppressed. In other words, an average current flowing through
the switching component 110 in an AC cycle will be substantially in
favor from the first node 111 which serves as an anode to the
second node 112 which serves as a cathode.
[0037] In an embodiment, the negative input node 122 and the
negative output node 124 are electrically connected.
[0038] Preferably, as shown in FIG. 2, the switching component 110
is a field-effect transistor (FET), where a bulk node of the FET
serves as the control-reference node 114, a gate node of the FET
serves as the control node 113, a source node of the FET serves as
one of the first node 111 and second nodes 112, and a drain node of
the FET serves as the other one of the first node 111 and second
nodes 112 according to the conducting type of the FET. For example,
if the FET is a FET with N conducting type, the drain node may
serve as the first node 111, and the source node may serve as the
second node 112. Additionally, in an embodiment, the control
reference node 114 is electrically connected to the first node 111
or the second node 112 upon the conducting type. That is, the
control reference node 114 may share the same node with the first
node 111 or the second node 112.
[0039] In an embodiment, as shown in FIG. 3, the switching
component 110 can also be a bipolar-junction transistor (BJT),
where a base node of the BJT serves as the high impedance control
node 113, a collector node of the BJT serves as one of the first
node 111 and second nodes 112, and an emitter node of the BJT
serves as the other one of the first node 111 and second nodes 112
according to the conducting type of the BJT. In this embodiment,
the control reference node 114 may be electrically connected to the
emitter node of the BJT or a substrate of the BJT.
[0040] It should be noted, that in the case of PMOS MOSFET, or PNP
BJT, the lower the gate voltage at 113, the higher the conduction
between the first node 111 and the second 112. For example, when
the switching component 110 is a PMOS that is controlled by a
voltage swing across the high-impedance control node 113 and the
first node 111 (i.e., V.sub.gs of the PMOS) and the control
reference node 114 is AC-coupled to the first node 111, and the
second node 112 is substantially DC-bypassed, the effective voltage
gain A.sub.v,eff from the first node 111 to the voltage swing
across the high-impedance control node 113 and the first node 111
(the control reference node 114) will be 1+|A.sub.v|. In this case,
A.sub.v will be out-of-phase with the input voltage swing at the
first node 111, so the AC voltage swing between the first node 111
and the second node 112 is substantially in phase with the
conductance therebetween. As such, if the gain A.sub.v is 2 with
180 degree phase shift, an effective gain A.sub.v,eff being 3 can
still be obtained. Therefore, assuming that the AC input voltage
V.sub.AC has a magnitude of 1 V and the voltage of the
high-impedance control node 113 (i.e., a gate voltage of the PMOS
MOSFET) is 2 V with 180 degree phase shift, the voltage swing
across the high-impedance control node 113 and the first node 111
(also the control reference node 114) will be 1+|2|=3V.
Furthermore, in the other case where the gain A.sub.v is 0.5, with
the same 1V input voltage swing, the high-impedance control node
113 will have a voltage of 0.5 V with 180 degree phase shift, the
voltage swing across the high-impedance control node 113 and the
first node 111 (also the control reference node 114) is 1.5 V
voltage which is still greater than the AC input voltage
V.sub.AC.
[0041] In an embodiment, the switching component 110 further
comprises a bias node for adjusting the conductance between the
first node and the second node. As such, the threshold voltage of
the switching component 110 can be compensated.
[0042] As illustrated in FIG. 4, a biasing circuit 140 electrically
connected to the high-impedance control node 113 is provided for
reducing an effective threshold voltage of the FET. In this
embodiment, the high-impedance control node 113 and the positive
output node 123 can be electrically connected through a capacitor
130, such that only the AC voltage swing from the impedance
transformer 120 can be permitted to the high-impedance control node
113. In other words, DC signal from the positive output node 123 is
suppressed by the capacitor 130. Although the biasing circuit 140
illustrated in FIG. 4 is implemented by a NMOS configuration,
various modifications to achieve an equivalent biasing function can
be made by persons skilled in the art. For example, in an
embodiment, the NMOS transistor can be replaced with a PMOS
transistor upon different biasing needs.
[0043] In an embodiment, as shown in FIG. 5, the biasing circuit
140 includes a diode-electrically connected transistor 141, a first
resistor 142 and a second resistor 143. The first resistor 142 is
electrically connected to the diode-electrically connected
transistor 141 to provide a bias voltage V.sub.REF when a current
generated by the diode-electrically connected transistor 141 flows
through the first resistor 142. Also, the second resistor 143 is
electrically connected to a node between the diode-electrically
connected transistor 141 and the first resistor 142, such that when
another end of the second resistor 143 is electrically connected to
the high-impedance control node 113, the second resistor 143 can
prevent the biasing circuit 140 from affecting the AC voltage swing
from the impedance transformer 120.
[0044] In an embodiment, the impedance transformer presents a
substantial 0.degree. phase shift if the switching device 110 is
typical, and presents a substantial 180.degree. phase shift if the
switching device 110 is complementary. It should be appreciated
that the switching device 110 is typical if a greater control
voltage increases the switching conductance thereof, while the
witching device 110 is complementary if a greater control voltage
decreases the switching conductance thereof.
[0045] FIG. 6 is a schematic circuit of the impedance transformer
120 according to an embodiment of the present invention. The
impedance transformer 120 presents a differential mode
configuration, and the sign of voltage gain can be swapped by
exchanging the positive output node 123 and the negative output
node 124, such that the outputted voltage swing is in phase with
the conductance between the first node 111 and the second node
112.
[0046] In an embodiment, the impedance transformer 120, as
illustrated in FIG. 6, includes a transformer unit, a first input
capacitor C.sub.1 and a shunt capacitor C.sub.shunt. The
transformer unit has a first coil L.sub.1 and a second coil
L.sub.2. A turn ratio of the first coil L.sub.1 to the second coil
L.sub.2 is 1 to a positive number N. The first input capacitor
C.sub.1 is electrically and serially connected between the positive
input node 121 and the first coil L.sub.1, and the shunt capacitor
C.sub.shunt is electrically connected between the positive output
node 123 and the negative output node 124 and is parallel to the
second coil L.sub.2.
[0047] In an embodiment, the impedance transformer 120 further
includes a second input capacitor C.sub.2 electrically and serially
connected between the negative input node 122 and the first coil
L.sub.1. Also, in an embodiment, the shunt capacitor C.sub.shunt
can be a parasitic capacitor contributed from an output load
thereof.
[0048] Further, as shown in FIG. 7, the impedance transformer 120
presents a common mode (single-ended) configuration, where the
negative input node 122 and the negative output node 124 can be
electrically connected, and the impedance transformer 120 provides
an out-of-phase voltage transfer function at some high frequencies,
i.e., providing an 180.degree. phase shift. In addition, it is
possible for the impedance transformer 120 to provide an in-phase
voltage transfer function at some very low frequencies, i.e.,
providing a 0.degree. phase shift.
[0049] In an embodiment, the impedance transformer 120, as
illustrated in FIG. 7, includes a first inductor L.sub.1, a second
inductor L.sub.2, a first shunt capacitor C.sub.1 and a second
shunt capacitor C.sub.shunt . The first inductor L.sub.1 is
electrically connected to the positive input node 121. The second
inductor L.sub.2 is electrically and serially connected between the
first inductor L.sub.1 and the positive output node 123. The first
shunt capacitor C.sub.1 is electrically connected across an
internal node X, which is electrically and serially connected
between the first inductor L.sub.1 and the second inductor L.sub.2,
and the negative input node 122. The second shunt capacitor
C.sub.shunt is electrically connected between the positive output
node 123 and the negative output node 124. In an embodiment, the
shunt capacitor C.sub.shunt can be a parasitic capacitor
contributed from an output load thereof.
[0050] FIG. 8 is a schematic circuit of a rectifier 200 according
to the present invention. The rectifier 200 has an AC input node
201, a DC input node 202, a DC output node 203 and a ground node
204, and converts AC signals to an output DC current. The rectifier
200 further includes first and second current-rectifying devices
100' and 100'' according to an embodiment mentioned above and first
and second capacitors C.sub.21 and C.sub.22.
[0051] Since the current-rectifying device 100 performs a function
similar to a traditional diode but with reduced effective forward
voltage drop and reverse leakage current and an increased forward
current, the current-rectifying devices are presented with a symbol
similar to a diode, where a thick line is on the first node or the
second node of the current-rectifying device to identify a terminal
with greater AC voltage swing. For example, as illustrated in FIG.
8, a thick line is on the second node 112' of the first
current-rectifying device 100' and a thick line is on the first
node 111'' of the second current-rectifying device 100''. The
positive input node 121 of the impedance transformer 120 is
typically connected to either the first node 111 or the second node
112 whichever has the maximum voltage swing to achieve best
current-rectifying performance. These symbols are used in later
figures.
[0052] As shown in FIG. 8, the first node 111' of the first
current-rectifying device 100' is electrically connected to the DC
input node 202, the second node 112' of the first
current-rectifying device 100' is electrically connected to another
end of the first capacitor C.sub.21, the first node 111'' of the
second current-rectifying device 100'' is electrically connected to
the another end of the first capacitor C.sub.21, and the second
node 112'' of the second current-rectifying device 100'' is
electrically connected to the DC output node 203. Also, the second
capacitor C.sub.22 is electrically connected across the DC output
node 203 and the ground node 204. As such, when an input AC voltage
signal V.sub.AC,in is applied to the AC input node 201, an output
DC current is obtained at the DC output node 203, and an output DC
voltage can be accordingly obtained with a load loaded to the DC
output node 203. In an embodiment, at least one of the switching
components 110 of the first and second current-rectifying devices
100' and 100'' further comprises a bias node for adjusting the
conductance between the first node 111', 111'' and the second node
112', 112'' of the first and second current-rectifying devices 100'
and 100'', respectively.
[0053] In the embodiment shown in FIG. 8, two current-rectifying
devices 100' and 100'' are employed to accomplish the rectifier
200. However, each impedance transformer of the current-rectifying
devices 100' and 100'' may occupy a significant space or layout
area and increase the cost. Accordingly, in an embodiment shown in
FIG. 9 the impedance transformers 120 can be merged into one
equivalent impedance transformer 220, such that an AC output
voltage swing from the equivalent impedance transformer 220 is
shared by using AC coupling capacitors 225 and 226 electrically
connected between equivalent output nodes of the equivalent
impedance transformer 220 and the high impedance control nodes 113'
and 113'' of the switching components 110' and 110'' in the first
and second current-rectifying devices 100' and 100''.
[0054] FIG. 10 is a schematic circuit of the rectifier 200
according to an embodiment of the present invention. As shown in
FIG. 10, the rectifier 200 further comprises an RF input node 231
for electrically connecting an external RF source 240 and a
matching network 230. The matching network 230 is electrically
connected to the RF input node 231 for matching the external RF
source 240 from the RF input node 231 to the AC input node 201, so
as to reduce a power reflection from the AC input node 201. Since
the means for matching an external RF source from an RF input node
to an AC input node is well-known in the art, specific description
regarding the matching network 230 is hereby omitted.
[0055] FIG. 11 is a schematic circuit of a multi-stage rectifier
300 according to the present invention. The multi-stage rectifier
300 has a multi-stage AC input node 301, a multi-stage DC positive
output node 302 and a multi-stage DC negative output node 303, and
converts AC signals to an output DC current. As shown in FIG. 11,
the multi-stage rectifier 300 includes a plurality of rectifiers
200 according to an embodiment mentioned above which are
electrically connected in a cascade configuration. In the cascade
configuration, the DC input node 202 of the rectifier 200 of a
first stage S.sub.1 is electrically connected to the multi-stage DC
negative output node 303, the DC output node 203 of the rectifier
200 of a next stage other than a last stage S.sub.M, i.e., one of
stages S.sub.1-S.sub.M-1, is electrically connected to the DC input
node 202 of the rectifier 200 of a succeeding stage which can be
one of stages S.sub.2-S.sub.M, the DC output node 203 of the
rectifier 200 of the last stage S.sub.M is electrically connected
to the multi-stage DC positive output node 302, and the AC input
nodes 201 of the rectifiers 200 of respective stages
S.sub.1-S.sub.M are electrically connected to the multi-stage AC
input node 301. Therefore, when an input AC voltage signal is
applied to the multi-stage AC input node 301, an output DC current
is obtained at the DC output node 302, and an output DC voltage can
be accordingly obtained with a load 350 electrically connected
between the multi-stage DC positive output node 302 and the
multi-stage negative output node 303.In an embodiment, at least one
of the switching components 110 of the first and second
current-rectifying devices 100', 100'' further comprises a bias
node for adjusting the conductance between the first node 111 and
the second node 112.
[0056] Typically, the bias nodes in the multi-stage rectifier 300
are biased by the multi-stage positive output node 302 with voltage
V.sub.DD or the multi-stage negative output node 303 with voltage
V.sub.SS as shown in the left part of FIG. 12. In an embodiment, in
order to further reduce DC power consumption of the multi-stage
rectifier 300, the voltage applying to each of the bias nodes is
not limited to the voltage V.sub.DD at the multi-stage positive
output node 302 or the voltage V.sub.SS at the multi-stage negative
output node 303. For example, in an exemplary 7-stages rectifier
300, each of the bias nodes of the switching components 100 in one
rectifier 200 can be connected in a progressive manner to one of
the DC output nodes 203 with voltages V.sub.B1 to V.sub.B5 or one
of the AC input nodes 201 with voltages V.sub.A1 to V.sub.A7 of
another rectifier 200 as shown in the right part of FIG. 12. It
should be appreciated that although FIG. 12 illustrates an
exemplary multi-stage rectifier 300 with 7 stages, the number of
stages of the multi-stage rectifier 300 is not limited to seven. In
fact, the number M of stages can be any number selected by persons
skilled in the art.
[0057] In the embodiment shown in FIG. 13, similar to the
embodiment shown in FIG. 9, the respective impedance transformers
120 in the multi-stage rectifier 300 can be merged into one
equivalent impedance transformer 320 having an equivalent positive
input node 321, equivalent negative input node 322, equivalent
positive output node 323 and equivalent negative output node 324,
such that an AC output voltage swing from the equivalent impedance
transformer 320 is shared by using multiple AC coupling capacitors
325, 326 electrically connected between equivalent output nodes of
the equivalent impedance transformer 320 and the high impedance
control nodes 113 of the switching components 110 in the
current-rectifying devices 100 of the rectifiers 200.
[0058] Specifically, in a multi-stage rectifier with both typical
and complementary switching component, the impedance transformer
120 of these current rectifying devices 200 can be categorized
based on their relative input and output phases. Generally, the
impedance transformers 120 can be categorized into four substantial
cases as the followings based on the phases of the impedance
transformer's input and output voltage swing:
[0059] 1.) In-phase input, in-phase output
[0060] 2.) In-phase input, out-of-phase output
[0061] 3.) Out-of-phase input, in-phase output
[0062] 4.) Out-of -phase input, out-of-phase output
[0063] The impedance transformers 120 can be merged by carrying a
two-step procedure. In a first step, the impedance transformers 120
are categorized based on the four cases above. Then, a second step
of merging is carried to obtain an equivalent impedance transformer
320. For example, all in-phase outputs are electrically connected
to the equivalent positive output node 323, all out-of-phase
outputs are electrically connected to the equivalent negative
output node 324, all in-phase inputs are electrically connected to
the equivalent positive input node 321, and all of out-of-phase
inputs are electrically connected to the equivalent negative input
node 322.
[0064] FIG. 14 is a schematic circuit of the multi-stage rectifier
300 according to an embodiment of the present invention. As shown
in FIG. 14, the multi-stage rectifier 300 further comprises an RF
input node 331 for electrically connecting an external RF source
340 and a matching network 330. The matching network 330 is
electrically connected to the RF input node 331 for matching the
external RF source 340 from the RF input node 331 to the AC input
node 301, so as to reduce a power reflection from the AC input node
301. Since the means of matching an external RF source from an RF
input node to an AC input node is well-known in the art, specific
description regarding the matching network 330 is hereby
omitted.
[0065] From the foregoing, the present invention provides a
current-rectifying device which reduces the effective forward
voltage drop and the leakage current, and increases the forward
current by employing an impedance transformer. As such, when the
current-rectifying device is used to form the IGR, the rectifier
achieves improved sensitivity and efficiency.
[0066] The above examples are only used to illustrate the principle
of the present invention and the effect thereof, and should not be
construed as to limit the present invention. The above examples can
all be modified and altered by those skilled in the art, without
departing from the spirit and scope of the present invention as
defined in the following appended claims.
* * * * *